Process for sizing paper



Patented May 19, 1931 PATENT OFFICE ERNEST LEOOOQ, OI BRUSSELS, IBELGIUI PROCESS FOR SIZING PAPER 110 bravin Application filed lay 1a, 1929, Serial in. 302,853, and in Belgium June a. ms.-

The present invention relates to a process for sizing paper, particularly to sizing with resin.

In the processes of this ty at present in (5] use, the bodies generally ad ed in the beating engine are composed of mineral and agglutinant resin soaps. Resin is for example converted into resin soap by an alkali such as sodium carbonate or sodium hydroxide. in These resin soaps (sizing milk) dissolve in the water and penetrate the fibres of the paper pulp contained in the beater. The resin is then precipitated on the fibres of the pulp by means of analuminium salt. An alum or sulphate or aluminium which decomposes the alkaline resinate or the resin soap is generally used. This decomposition takes place in' an acid medium.

The disadvantages of the majority of these processes are their high cost, the presence ofimpurities and the fouling of the metal gauze owing to the 10w solubility of the materials.

The object of the present invention is to remove these disadvantages and to facilitate resin'sizing and colouringof the paper, us ing a product of low value.

According to the invention, a bi-sulphate of an alkaline metal is used for this purpose either alone with the agglutinant, or mixed with other mineral and vegetable substances, particularly aluminium sulphate.

A process carried out according to the invention is described below by way of example. 40 gms. of alkaline resinate obtained by solved in one litre of hot water and the solution is poured into the beater containing 200 kgs. of the paper pulp to be sized. A second preparation is obtained by dissolving 180' gms. of aluminium sulphate and 200 gms. of

sodium bi-sulphate in water, the mixture being poured into the beater already containing the resinate. The solutions of sodium'bisulphate and aluminium sulphate are preferably added separately. The solution of bisulphate is poured intov the beater some time (if possible half an hour) after the resinate and the solution of aluminium sulphate some a time after the bi-sulphate (if possible a quarter of an hour). The bi-sulphate solution is the action of an alkaline salt on resin are dispreferably added before the aluminium sulphate in a tank containing the paper pulp. If the resultant sizing is insuflicient, aluminium sulphate is preferably added. The acidity of the pul can then be wholly or ,partially neutralize 'in any known manner by means of a base or calcium carbonate. About 1 kg. of powdered chalk is preferably used for each kg. of sulphuric acid (66 B.) to be neutralized. The charge is comleted in order to'give the desired percentage by adding an inert substance such as kaolin.

A paper of better quality than by any other process is obtained, the retail price of which is five or six times less. It is to be noted 05 that the acid sulphates ofthe alkaline metals are obtained in a purer form than aluminium sulphate.- They are more easily freed from iron and are better mordants for fixing dyes, etc.

This process using alkaline bi-sulphate alone is used for ordinary papers and papers comprising old sized papers. The combined process using aluminium sulphate is appl1ca ble to'all klIldS of paper but for complete 7 sizing-(strong size) it is preferable to use a .;third of aluminium'sulphate, I kg. of sodium bi-sulphate replacing 2.5 kgs., of aluminium sulphate.

It isobvious that the constituents can be varied but one of the solutions used for the sizing must always, according to the invention, contain a sulphate or bi-sulphate of an alkaline metal.

p The relative proportions of each of the constituents are not fixed and can bevaried according to the desires of individual customers and according to the price to be. paid.

What I claim is:

1. In a process for sizing paper by means of an agglutinant constitutin a resin soap, treatin said resin soap and t e paper pulp with blsulfate of an alkaline metal.

.2. In a processfor sizingpaper by means of an agglutinant constituting a resin soap. treating said resin soap and the paper pulps with bisulphate of an alkaline metal used in the form of a solution of sodium bisulphate.

3. In a process for sizing paper by means of an agglutinant constituting a'resin soap,

treating said resin soap and the paper pulp with a solution of a bisulphate of an alkaline metal and a solution of aluminium sulphate.

4. In a process for si zing'paper by means 5 of an agglutinant constituting a resin soap, treating said resin soap and the paper pulp with a solution of bisulphate of an alkaline metal and treating the mixture afterwards M with a solution of aluminium sulphate.

w 5. In a lprocess for sizing paper by means of an agg utinant constituting a resin soap, mixing a solution of a bisulphate of an alkaline metal with a solution of aluminium sulphate and treating the resin soap and paper 5 pulp withthe said mixture.

6., In a process for sizing paper bymeans of an agglutinant constituting a resin soap, treating said resin soap and the paper pu p with a solution of approximately three parts 7 -30 of sodium bisulphate and a solution of two parts of aluminium sulphate. 4

7.- In a process for sizingpaper by means of an agglutinant constitutin a resin soap, treating said resin soap and t e paper pulp with bisulphate ofan alkaline metal, and neutralizing the acidity of the paper pulp by a base. g

8. In a process for sizing paper by means of an agglutinant constituting a resin soap, treating said resin soap and the paper pulp with bisulphate of an alkaline metal and neutralizing the acidity of the paper pulp by calcium carbonate. l 9. In a process for sizing paper by means of an agglutinant constituting a resin soap, treating said resin soap and the paper pulp with bisulphate of an alkaline metal andneutralizing the acidity of the paper pulp by 1 powdered chalk.

40 In testimony whereof I have aflixied my signature,

. ERNEST LECOCQ. 

